Peptide hormones, cytokines and neuropeptides are signaling molecules that play key roles in normal physiology and disease states. Traditional immunoassays for these secreted proteins, such as the enzyme-linked immunosorbant assay (ELISA) and radioimmunoassay, have enabled limited investigation into the pathways regulating their secretion, yet these assays are too expensive and time-consuming to be useful for large-scale chemical and genetic screening. Thus, a need exists for a high-throughput method of tracking peptide secretion or cell surface expression of a peptide.
A particular secreted peptide of interest is insulin. Failure to maintain adequate insulin secretion is central to the pathogenesis of both type 1 and type 2 diabetes. Determining the genetic pathways that regulate insulin secretion and finding small molecule probes of these pathways would greatly advance our understanding of the beta cell and bring us closer to a cure for both forms of diabetes. However, high throughput screens of insulin secretion using genetic (e.g., RNAi) or chemical perturbations are currently impracticable due to the lack of an amenable assay for measuring secreted insulin. Insulin ELISA kits and radioimmunoassays are not well suited to this application due to their expense, complicated handling requirements and restriction to 96-well format. Thus, a need exists for a high-throughput method of tracking peptide secretion, in particular, insulin hormone secretion.